Abstract

BACKGROUND: The copy number of donor-derived cell-free DNA (dd-cfDNA) in blood correlates with acute rejection (AR) in heart transplantation. We analyzed urinary dd-cfDNA as a surrogate marker of kidney transplant injury. METHODS: Sixty-three biopsy-matched urine samples (41 stable and 22 allograft injury) were analyzed from female recipients of male donors for chromosome Y (donor)-specific dd-cfDNA. All biopsies were semiquantitatively scored by a single pathologist. Standard statistical measures of correlation and significance were used. RESULTS: There was baseline scatter for urinary dd-cfDNA/?g urine creatinine across different patients, even at the time of stable graft (STA) function (undetected to 12.26 copies). The mean urinary dd-cfDNA in AR (20.5±13.9) was significantly greater compared with STA (2.4±3.3; P<0.0001) or those with chronic allograft injury (CAI; 2.4±2.4; P=0.001) but no different from BK virus nephropathy (BKVN; 20.3±15.7; P=0.98). In AR and BKVN, the intrapatient drift was highly significant versus STA or CAI patients (10.3±7.4 in AR; 12.3±8.4 in BKVN vs. -0.5±3.5 in STA and 2.3±2.6 in CAI; P<0.05). Urinary dd-cfDNA correlated with protein/creatinine ratio (r=0.48; P<0.014) and calculated glomerular filtration rate (r=-0.52; P<0.007) but was most sensitive for acute allograft injury (area under the curve=0.80; P<0.0006; 95% confidence interval, 0.67-0.93). CONCLUSION: Urinary dd-cfDNA after renal transplantation has patient specific thresholds, reflecting the apoptotic injury load of the donor organ. Serial monitoring of urinary dd-cfDNA can be a surrogate sensitive biomarker of acute injury in the donor organ but lacks the specificity to distinguish between AR and BKVN injury.

Abstract

The development of anti-donor humoral responses after transplantation associates with higher risks for acute rejection and 1-year graft survival in adults, but the influence of humoral immunity on transplant outcomes in children is not well understood. Here, we studied the evolution of humoral immunity in low-risk pediatric patients during the first 2 years after renal transplantation. Using data from 130 pediatric renal transplant patients randomized to steroid-free (SF) or steroid-based (SB) immunosuppression in the NIH-SNSO1 trial, we correlated the presence of serum anti-HLA antibodies to donor HLA antigens (donor-specific antibodies) and serum MHC class 1-related chain A (MICA) antibody with both clinical outcomes and histology identified on protocol biopsies at 0, 6, 12, and 24 months. We detected de novo antibodies after transplant in 24% (23% of SF group and 25% of SB group), most often after the first year. Overall, 22% developed anti-HLA antibodies, of which 6% were donor-specific antibodies, and 6% developed anti-MICA antibody. Presence of these antibodies de novo associated with significantly higher risks for acute rejection (P=0.02), chronic graft injury (P=0.02), and decline in graft function (P=0.02). In summary, antibodies to HLA and MICA antigens appear in approximately 25% of unsensitized pediatric patients, placing them at greater risk for acute and chronic rejection with accelerated loss of graft function. Avoiding steroids does not seem to modify this incidence. Whether serial assessments of these antibodies after transplant could guide individual tailoring of immunosuppression requires additional study.

Abstract

Monitoring of renal graft status through peripheral blood (PB) rather than invasive biopsy is important as it will lessen the risk of infection and other stresses, while reducing the costs of rejection diagnosis. Blood gene biomarker panels were discovered by microarrays at a single center and subsequently validated and cross-validated by QPCR in the NIH SNSO1 randomized study from 12 US pediatric transplant programs. A total of 367 unique human PB samples, each paired with a graft biopsy for centralized, blinded phenotype classification, were analyzed (115 acute rejection (AR), 180 stable and 72 other causes of graft injury). Of the differentially expressed genes by microarray, Q-PCR analysis of a five gene-set (DUSP1, PBEF1, PSEN1, MAPK9 and NKTR) classified AR with high accuracy. A logistic regression model was built on independent training-set (n = 47) and validated on independent test-set (n = 198)samples, discriminating AR from STA with 91% sensitivity and 94% specificity and AR from all other non-AR phenotypes with 91% sensitivity and 90% specificity. The 5-gene set can diagnose AR potentially avoiding the need for invasive renal biopsy. These data support the conduct of a prospective study to validate the clinical predictive utility of this diagnostic tool.

Abstract

Steroid avoidance is safe and effective in children receiving kidney transplants in terms of graft function and survival, but the effects on allograft histology are unknown. In this multicenter trial, 130 pediatric renal transplant recipients were randomized to steroid-free (SF; n = 60) or steroid-based (SB; n = 70) immunosuppression, and underwent renal allograft biopsies at the time of graft dysfunction and per protocol at implantation and 6, 12 and 24 months after transplantation. Clinical follow-up was 3 years posttransplant. Subclinical acute rejection was present in 10.6% SF versus 11.3% SB biopsies at 6 months (p = 0.91), 0% SF versus 4.3% SB biopsies at 1 year (p = 0.21) and 0% versus 4.8% at 2 years (p = 0.20). Clinical acute rejection was present in 13.3% SF and 11.4% SB patients by 1 year (p = 0.74) and in 16.7% SF and 17.1% SB patients by 3 years (p = 0.94) after transplantation. The cumulative incidence of antibody-mediated rejection was 6.7% in SF and 2.9% in SB by 3 years after transplantation (p = 0.30). There was a significant increase in chronic histological damage over time (p < 0.001), without difference between SF and SB patients. Smaller recipient size and higher donor age were the main risk factors for chronic histological injury in posttransplant biopsies.

Abstract

The degree of progressive chronic histological damage is associated with long-term renal allograft survival. In order to identify promising molecular targets for timely intervention, we examined renal allograft protocol and indication biopsies from 120 low-risk pediatric and adolescent recipients by whole-genome microarray expression profiling. In data-driven analysis, we found a highly regulated pattern of adaptive and innate immune gene expression that correlated with established or ongoing histological chronic injury, and also with development of future chronic histological damage, even in histologically pristine kidneys. Hence, histologically unrecognized immunological injury at a molecular level sets the stage for the development of chronic tissue injury, while the same molecular response is accentuated during established and worsening chronic allograft damage. Irrespective of the hypothesized immune or nonimmune trigger for chronic allograft injury, a highly orchestrated regulation of innate and adaptive immune responses was found in the graft at the molecular level. This occurred months before histologic lesions appear, and quantitatively below the diagnostic threshold of classic T-cell or antibody-mediated rejection. Thus, measurement of specific immune gene expression in protocol biopsies may be warranted to predict the development of subsequent chronic injury in histologically quiescent grafts and as a means to titrate immunosuppressive therapy.

Abstract

Children with small capacity, defunctionalized urinary bladders present unique operative challenges. Thus, traditional practice has included pretransplant bladder augmentation, but this has several adverse consequences.A single-institutional, retrospective review from January 1, 2004 to December 31, 2008 was conducted. Twelve pediatric patients, whom had not undergone pretransplant bladder augmentation, did not have neurogenic bladders or require preoperative catheterization, and a small capacity defunctionalized bladders were included. All were managed by the same surgeon with a previously described ureteral implantation, and a 7F ureteral stent attached to a large diameter suprapubic catheter was removed in a joint manner without cystoscopy at 2 weeks. Data were collected on patient and graft survival, rejection episodes, urinary tract infection (UTI) requiring antibiotics, grade of vesicoureteral reflux, and posttransplant bladder capacity.One-year patient and graft survival rates were 100%. One patient experienced a clinical rejection episode, which was successfully treated. Five patients (41.7%) had a UTI requiring abx treatment within the first postoperative year, but at 1 year, all patients had sterile urinary tracts. After removal of suprapubic catheters and ureteral stents, all patients were able to void spontaneously. Seven patients had no posttransplant ureteral reflux, three had grade 1 reflux, and two had grade 3 reflux (both successfully treated). The average age estimated pretransplant bladder and 1 year posttransplant bladder capacity was 14.5% and 84% of expected, respectively.In pediatric end-stage renal disease patients with a small capacity defunctionalized bladder, it is reasonable to proceed with kidney transplantation without pretransplant bladder augmentation, thus avoiding an unnecessary surgery.

Abstract

Given the recent withdrawal of daclizumab (DAC), the safety and efficacy of thymoglobulin (TMG) was tested as an alternative induction agent for steroid-free (SF) immunosuppression in pediatric kidney transplant recipients.Thirteen pediatric renal transplant recipients meeting defined high-risk criteria at transplantation were offered TMG induction and SF immunosuppression with maintenance mycophenolate mofetil and tacrolimus between October 2008 and January 2010. Patients were closely monitored at baseline, 3, 6, 9, and 12 months posttransplant for protocol biopsy and clinical outcomes. Outcomes were compared with 13 consecutively transplanted low-risk patients receiving an established DAC-based SF protocol (Sarwal et al., WA, American Transplant Congress 2003).There was a significant trend for overall decrease in the absolute lymphocyte counts in TMG group (F=5.86, mixed model group effect P=0.02), predominately at 3 months compared with DAC group (0.7±0.6 vs. 2.1±1.0, P=0.0004); however, lymphocyte count was recovered and was back to reference range by 6 months in TMG. There was trend toward more subclinical cytomegalovirus (15% vs. 0%) and BK viremia (17% vs. 0%) in the TMG group, with no differences in the incidence of subclinical Epstein Barr virus viremia (23% vs. 31%) or clinical viral disease. Mean graft function was excellent, and with a minimum follow-up of 6 months, there were no episodes of acute rejection.TMG seems to be a safe alternative induction strategy in patients for SF immunosuppression in pediatric renal transplantation. Extended follow-up and greater enrollment are necessary to fully explore the impact of TMG dosing on viral replication posttransplantation.

Abstract

Small pediatric recipients of an adult-sized kidney have insufficient renal blood flow early after transplantation, with secondary chronic hypoperfusion and irreversible histological damage of the tubulo-interstitial compartment. It is unknown whether this is reflected by renal resistive indices. We measured renal graft resistive indices and volumes of 47 healthy pediatric kidney transplant recipients of an adult-sized kidney in a prospective study for six months post-transplant. A total of 205 measurements were performed. The smallest recipients (BSA or= 1.5 m(2) (p < 0.0001). Resistive indices increased during the first six months in the smallest recipients (p = 0.02), but not in the two larger recipient groups (BSA 0.75-1.5 m(2) and >or=1.5 m(2)). All three BSA groups showed a reduction in renal volume after transplantation, with the greatest reduction occurring in the smallest recipients. In conclusion, renal transplant resistive indices reflect pediatric recipient BSA dependency. The higher resistance to intra-renal vascular flow and significant decrease in renal volume in the smallest group likely reflect accommodation of the size discrepant transplanted adult-sized kidney to the smaller pediatric recipient vasculature with associated lower renal artery flow.

Abstract

Acute rejection episodes are almost inevitable in the face of immunosuppression non-adherence and a known risk factor for developing chronic allograft nephropathy and accelerated graft loss. Daclizumab, a humanized monoclonal antibody directed against the alpha chain of the IL-2 receptor, is an important advance for induction therapy in renal transplant immunosuppression, reducing early acute graft rejection without affecting the tolerability of standard immunosuppression, for both steroid-based and steroid-free immunosuppressive protocols, in children and adults. In the absence of depot immunosuppression for maintenance therapy, we explored extended daclizumab therapy as temporary maintenance immunosuppression for acute rejection prophylaxis in two patients with recalcitrant immunosuppression non-adherence. Both patients had prior episodes of aggressive acute rejection associated with their non-adherence but achieved stable and rejection-free renal allograft function with daclizumab monotherapy in the presence of documented non-adherence thus providing an effective bridge for up to 12 months until immunosuppression adherence was re-established with ongoing psychosocial support. This report suggests that daclizumab monotherapy over an extended period of time during the period of non-adherence in the post transplant period could be a rescue modality to avoid immune activation and thereby prevent acute rejection in the face of erratic maintenance immunosuppression.

Abstract

A disparity remains between graft survival of renal allografts from deceased donors and from living donors. A better understanding of the molecular mechanisms that underlie this disparity may allow the development of targeted therapies to enhance graft survival. Here, we used microarrays to examine whole genome expression profiles using tissue from 53 human renal allograft protocol biopsies obtained both at implantation and after transplantation. The gene expression profiles of living-donor kidneys and pristine deceased-donor kidneys (normal histology, young age) were significantly different before reperfusion at implantation. Deceased-donor kidneys exhibited a significant increase in renal expression of complement genes; posttransplantation biopsies from well-functioning, nonrejecting kidneys, regardless of donor source, also demonstrated a significant increase in complement expression. Peritransplantation phenomena, such as donor death and possibly cold ischemia time, contributed to differences in complement pathway gene expression. In addition, complement gene expression at the time of implantation was associated with both early and late graft function. These data suggest that complement-modulating therapy may improve graft outcomes in renal transplantation.

Abstract

Short-term outcomes using steroid-free immunosuppression after renal transplantation have been promising. No studies have examined the incidence of and reasons for steroid-avoidance protocol failures.We present a single-center analysis of steroid-free immunosuppression failures among 129 pediatric renal transplant recipients with mean follow-up of 5 years. We analyzed causes for failure and examined reasons for conversion to steroid-based therapy. We compared actual patient and allograft survival and allograft function in the cohort of patients who required conversion to steroid-based immunosuppression with that of the cohort maintaining steroid-free immunosuppression.A total of 13.2% (17/129) of patients failed steroid-free immunosuppression. Actual patient survival was equivalent in the two cohorts, 96.4% for the cohort maintaining steroid-free immunosuppression and 94.1% for those requiring conversion. Actual allograft survival was lower in patients requiring conversion to a steroid-based protocol, 76.5% vs. 95.5% (P=0.004). Estimated glomerular filtration rates 12-months and 24-months posttransplant were greater in patients maintaining steroid-free immunosuppression (P=0.003). Most patients (52.9%, 9/17) who broke the steroid-free protocol did so because of refractory acute rejection. The second most common reason was recurrence of glomerulonephritis (GN; 35.3%, 6/17).The failure rate of steroid-free immunosuppression among selective pediatric patients undergoing renal transplantation is low. Patients maintaining steroid-free immunosuppression have better allograft survival and function than those requiring conversion to steroid-based therapy. The most common reasons for failure of steroid-free immunosuppression are recalcitrant or recurrent allograft rejection and recurrent GN; the role of conversion to steroid-based immunosuppression after episodes of acute rejection and recurrent GN requires additional analysis.

Abstract

We report 1-year outcomes of a randomized study of Rituximab versus standard-of-care immunosuppression (Thymoglobulin and/or pulse steroids) for treatment of biopsy confirmed, acute transplant rejection with B-cell infiltrates, in 20 consecutive recipients (2-23 years). Graft biopsies, with Banff and CADI scores, CD20 and C4d stains, were performed at rejection and 1 and 6 months later. Peripheral blood CMV, EBV and BK viral loads, graft function, DSA, immunoglobulins, serum humanized antichimeric antibody (HACA) and Rituximab, and lymphocyte counts were monitored until 1 year posttreatment. Rituximab infusions were given with a high index of safety without HACA development and increased infections complications. Rituximab therapy resulted in complete tissue B-cell depletion and rapid peripheral B-cell depletion. Peripheral CD19 cells recovered at a mean time of approximately 12 months. There were some benefits for the recovery of graft function (p = 0.026) and improvement of biopsy rejection scores at both the 1- (p = 0.0003) and 6-month (p < 0.0001) follow-up biopsies. Reappearance of C4d deposition was not seen on follow-up biopsies after Rituximab therapy, but was seen in 30% of control patients. There was no change in DSA in either group, independent of rejection resolution. This study reports safety and suggests further investigation of Rituximab as an adjunctive treatment for B-cell-mediated graft rejection.

Abstract

Children with end-stage renal disease and inferior vena cava (IVC) thrombosis are rare, and their condition is complex and high risk for renal transplantation. Detailed imaging studies of the recipient's abdominal vasculature should be carried out prior to transplantation, followed by careful pre-operative joint planning by the pediatric transplant surgeon and nephrologist. Critical decisions need to be made as to whether a deceased child's kidney or an adult-sized kidney is to be used, and if the latter, whether it should be from a deceased or living donor. In addition, the contemplated site of the donor's renal vein anastomosis needs to be determined with a consideration of the possible consequences of the various choices. Sixteen cases of renal transplantation in children with pre-existing IVC thrombosis are reviewed, including the three reported by Shenoy et al. in this journal. With a full understanding of the difficulties noted, renal transplantation in a small child with IVC thrombosis can be successful. However, it requires thorough recipient assessment, coupled with a careful and thoughtful examination of options, to determine the best possible approach to the transplantation.

Abstract

With the increasing adoption of steroid-sparing immunosuppression protocols in renal transplantation, it is important to evaluate any adverse effects of steroid avoidance on graft function. Early graft function, measured by CrCl was retrospectively studied in 158 consecutive pediatric renal transplant recipients from 1996 to 2005, receiving either steroid-free or steroid-based immunosuppression. Patients receiving steroid-free immunosuppression vs. steroid-based immunosuppression had no difference change in CrCl (DeltaCrCl) in the first week post-transplantation (p = 0.12). When stratified by corticosteroid usage, patients with higher tacrolimus trough levels (> or =14 ng/mL) had slower graft function recovery in the first week post-transplantation than those with lower tacrolimus trough levels (p = 0.008) in the steroid-free group only. Despite initial slower graft function recovery in this subgroup, there was no negative impact on graft function in the steroid-free group; in fact steroid-free patients trended towards better CrCl at six months (p = 0.047) and 12 months (p < 0.001) post-transplant than the steroid-based group. With the improved immunological outcomes with steroid avoidance, close surveillance should be performed of tacrolimus levels to avoid levels >14 ng/mL. In patients with slow recovery of early graft function, short-term perioperative steroids may be considered.

Abstract

Intra-graft CD20(+) B-cell clusters are found during acute rejection of renal allografts and correlate with graft recovery following rejection injury. Here using archived kidney tissue we conducted immunohistochemical studies to measure specific subsets of pathogenic B cells during graft rejection. Cluster-forming CD20(+) B cells in the rejected graft are likely derived from the recipient and are composed of mature B cells. These cells are activated (CD79a(+)), and present MHC Class II antigen (HLADR(+)) to CD4(+) T cells. Some of these clusters contained memory B cells (CD27(+)) and they did not correlate with intra-graft C4d deposition or with detection of donor-specific antibody. Further, several non-cluster forming CD20(-) B-lineage CD38(+) plasmablasts and plasma cells were found to infiltrate the rejected grafts and these cells strongly correlated with circulating donor-specific antibody, and to a lesser extent with intra-graft C4d. Both CD20(+) B cells and CD38(+) cells correlated with poor response of the rejection to steroids. Reduced graft survival was associated with the presence of CD20 cells in the graft. In conclusion, a specific subset of early lineage B cells appears to be an antigen-presenting cell and which when present in the rejected graft may support a steroid-resistant T-cell-mediated cellular rejection. Late lineage interstitial plasmablasts and plasma cells may also support humoral rejection. These studies suggest that detailed analysis of interstitial cellular infiltrates may allow better use of B-cell lineage specific treatments to improve graft outcomes.

Abstract

In contrast to adult kidney recipients, in whom the long-term evolution and clinical determinants of tacrolimus pharmacokinetics are well studied, less is known about the long-term evolution of tacrolimus pharmacokinetics in pediatric kidney transplant recipients.One-hundred and five pediatric recipients of a kidney allograft, all treated with a corticosteroid-free immunosuppressive protocol, were included. The evolution of tacrolimus doses and predose trough (C0) levels was recorded at 3, 6, 9, 12, 18, and 24 months after transplantation, as well as all C0 levels obtained in the first 2 years after transplantation. The evolution and clinical determinants of tacrolimus exposure parameters were analyzed.Dose-corrected tacrolimus C0 levels (C0/dose/kg) increased in the first 2 years after kidney transplantation in pediatric recipients (P=0.001). This decrease in dose requirement by time was only significant in children older than 5 years at the time of transplantation (P=0.38, 0.03, and 0.001 for age groups <5, 5-12, and >12 years, respectively). In addition, the younger patients had significantly higher dose requirements (dose/kg) compared with older recipients (P=0.0002).Pediatric kidney transplant recipients exhibit maturation of dose-corrected tacrolimus predose trough levels with time after transplantation. This cannot be explained by differences in corticosteroid use, because all patients were treated with a corticosteroid-free protocol. The higher dose requirements for younger recipients and the absence of tacrolimus maturation in the youngest recipients suggest that age-dependent changes in tacrolimus intestinal first-pass effect, metabolism, or distribution play a role. Whether age-specific tacrolimus dosing algorithms will improve outcome needs further study.

Abstract

To describe the evolution, risk factors and impact of nonimmune histological injury after pediatric kidney transplantation, we analyzed 245 renal allograft protocol biopsies taken regularly from the time of transplantation to 2 years thereafter in 81 consecutive rejection-free pediatric recipients of an adult-sized kidney. Isometric tubular vacuolization was present early after transplantation was not progressive, and was associated with higher tacrolimus pre-dose trough levels. Chronic tubulo-interstitial damage and tubular microcalcifications were already noted at 3 months, were progressive and had a greater association with small recipient size, male donor gender, higher donor age and female recipient gender, but not with tacrolimus exposure. Renal function assessment showed that older recipients had a significant increase in absolute glomerular filtration rate with time after transplantation, which differed from small recipients who showed no increase. It is concluded that progressive, functionally relevant, nonimmune injury is detected early after adult-sized kidney transplantation in pediatric recipients. Renal graft ischemia associated with the donor-recipient size discrepancy appears to be a greater risk factor for this chronic histological injury, suggesting that the exploration of additional therapeutic approaches to increase allograft perfusion could further extend the graft survival benefit of adult-sized kidneys transplanted into small children.

Abstract

Long-term allograft survival generally requires lifelong immunosuppression (IS). Rarely, recipients display spontaneous "operational tolerance" with stable graft function in the absence of IS. The lack of biological markers of this phenomenon precludes identification of potentially tolerant patients in which IS could be tapered and hinders the development of new tolerance-inducing strategies. The objective of this study was to identify minimally invasive blood biomarkers for operational tolerance and use these biomarkers to determine the frequency of this state in immunosuppressed patients with stable graft function. Blood gene expression profiles from 75 renal-transplant patient cohorts (operational tolerance/acute and chronic rejection/stable graft function on IS) and 16 healthy individuals were analyzed. A subset of samples was used for microarray analysis where three-class comparison of the different groups of patients identified a "tolerant footprint" of 49 genes. These biomarkers were applied for prediction of operational tolerance by microarray and real-time PCR in independent test groups. Thirty-three of 49 genes correctly segregated tolerance and chronic rejection phenotypes with 99% and 86% specificity. The signature is shared with 1 of 12 and 5 of 10 stable patients on triple IS and low-dose steroid monotherapy, respectively. The gene signature suggests a pattern of reduced costimulatory signaling, immune quiescence, apoptosis, and memory T cell responses. This study identifies in the blood of kidney recipients a set of genes associated with operational tolerance that may have utility as a minimally invasive monitoring tool for guiding IS titration. Further validation of this tool for safe IS minimization in prospective clinical trials is warranted.

Abstract

This report describes an unusual presentation of severe hypertension (HTN) in a subset of pediatric kidney recipients treated with a steroid avoidance pediatric renal transplantation protocol. The HTN was secondary to atypical, reno-vascular abnormalities (RVA) of the transplanted vasculature, temporally associated with erythropoietin (EPO) use.To investigate the clinical significance underlying this event, a retrospective clinical study of 100 pediatric renal transplants was undertaken (50 steroid-free and 50 matched steroid-based controls), with peripheral blood transcriptional analysis of four RVA patients and controls.Regardless of a higher observed incidence of anemia (p < 0.001) and greater overall EPO usage in the first post-transplant year in steroid-free patients, the incidence of new-onset HTN at one yr was significantly less in the steroid-free cohort (p = 0.03). Nevertheless, early EPO (first week post-transplant) was significantly associated with the combinatory findings of new-onset HTN (p = 0.03) and RVA (p = 0.007). Molecular mechanisms of RVA injury were investigated further by peripheral blood cDNA microarray gene expression profiling. A panel of 42 transcripts differentiated patients with RVA and HTN from three sets of matched controls, with and without HTN and EPO use, with 100% concordance (p < 0.001). The biological processes governed by these significant genes suggest a role for EPO regulation of growth factor receptor ubiquitination as a putative mechanism for renal vascular injury.This study cautions against the use early post-transplant use of EPO in immunosuppression regimens with steroid minimization/avoidance, which may have an increased incidence of post-transplant anemia.

Abstract

A retrospective analysis was conducted on 10 consecutive cases of neonatal ARPKD, 9 of whom received kidney transplants (KT). All were diagnosed antenatally (n = 6) or at birth. In the first month of life 70% required ventilatory support. Pre-emptive bilateral nephrectomy and peritoneal dialysis (PD) catheter placement were performed in 9 at a mean age of 7.8 +/- 11.9 months. The indications for nephrectomy were massive kidneys, resulting in suboptimal nutrition and respiratory compromise. All patients received assisted enteral nutrition, with significant increase in mean tolerated feeds following nephrectomy (p < 0.05), with increase in mean normalized weight and height (0.92 and 1.2 delta SDS respectively), by one year post-transplantation. KT was performed at a mean age and weight of 2.5 +/- 1.4 years and 13.3 +/- 6.1 kg. The mean creatinine clearance at one year post-KT was 91.3 +/- 38.1 mls/min/1.73 m(2), with a projected graft life expectancy of 18.4 years. Patient survival was 89% and death censored graft survival was 100%, at a mean follow-up of 6.1 +/- 4.5 years post-transplant. Six patients demonstrated evidence of hepatic fibrosis, one of which required liver transplantation. In patients with massive kidneys from ARPKD, pre-emptive bilateral nephrectomy, supportive PD and early aggressive nutrition, can minimize early infant mortality, so that subsequent KT can be performed with excellent patient and graft survival.

Abstract

Although normative values of post-transplant proteinuria have been reported in adults, data for pediatric renal transplant recipients have not been previously published. We hypothesized that pediatric renal transplant recipients achieve normal urinary protein to creatinine (UProt/UCr) ratios (<0.2) by 60 days post-transplant in the absence of early recurrent disease. Retrospective chart review of 108 consecutive pediatric renal transplant recipients at Stanford University was performed. Thirty-two (30%) patients who were eligible had > or = 1 UProt/UCr ratio obtained during the first 60 post-transplant days. Mean age at transplant was 13.9 +/- 4.2 yr. UProt/UCr ratios were grouped by week post-transplant for quantile analysis. Mean weekly UProt/UCr values were not lower than 0.2 until the ninth post-transplant week. No difference in post-transplant proteinuria existed between nephrectomized and non-nephrectomized transplant recipients. Experience with a single patient with proven focal segmental glomerulosclerosis (FSGS) recurrence suggests that normative UProt/UCr data may be useful in early identification of patients experiencing disease recurrence. Univariate correlations demonstrated that UProt/UCr negatively correlated with serum albumin levels (-0.415, p < 0.0001) and days post-transplant (-0.531, p < 0.0001). Independent of primary diagnosis, proteinuria persists throughout the first 60 days in most pediatric renal transplant patients, decreasing relative to time post-transplant.

Abstract

Inferior vena cava (IVC) thrombosis is generally a contraindication to renal transplantation in small children because of the technical difficulty and limitations in allograft venous outflow drainage that risk graft thrombosis.The records of six consecutive children (9.9-27.4 kg) with end-stage renal disease and thrombosed IVCs were reviewed. Small deceased donor renal allografts were utilized in all cases where immediate posttransplant venous renal outflow would theoretically not exceed the drainage capacity of the iliac or adjacent pelvic collateral veins.There is 100% patient survival with two patients returning to dialysis at seven and three years posttransplantation. There were no surgical complications or delayed graft function. Postoperatively, progressive renal vein and simultaneous iliac venous enlargement was observed in five of six recipients concomitant with renal allograft enlargement. In these patients, maximum renal volume achieved was between 152 and 275 ml and last recorded Schwartz glomerular filtration rates ranged from 67 to 118 ml/min. The sixth allograft had an early, severe rejection episode that limited renal growth and attainment of good renal function. All patients demonstrated resumption of growth rates commensurate with age but without significant catch-up growth.A small deceased donor kidney can provide freedom from dialysis and better quality of life for small children with IVC thrombosis during an age when dialysis treatment is difficult and the complications of the thrombosed IVC may compromise life. Good renal function was attained in patients without rejection episodes. In those with rejection, our approach allowed for patient growth during allograft function, providing a bridge for a repeat transplant.

Abstract

Renal transplantation in the pediatric population, although conceptually similar to that in adults, differs in many aspects. This review will focus on the issues unique to the pediatric recipient. In particular, we will focus on the incidence and etiology of end stage renal disease in children, and the results as measured by patient and graft survival. Pretransplant surgical considerations of timing of the transplant, management of congenital urologic abnormalities and the abnormal bladder will be addressed. Etiologies of renal failure unique to the pediatric population will be discussed, including autosomal recessive polycystic kidney disease, congenital nephrotic syndrome, inferior vena cava thrombosis, and primary hyperoxaluria Type 1. Lastly, special transplant surgical considerations including transplantation of an adult-size kidney (ASK) into an infant or small child and ureteral implantation, management of the urinary bladder, and fluid management in infants and small children will be discussed.

Abstract

The causes and clinical course of acute rejection vary, and it is not possible to predict graft outcome reliably on the basis of available clinical, pathological, and genetic markers. We hypothesized that previously unrecognized molecular heterogeneity might underlie some of the variability in the clinical course of acute renal allograft rejection and in its response to treatment.We used DNA microarrays in a systematic study of gene-expression patterns in biopsy samples from normal and dysfunctional renal allografts. A combination of exploratory and supervised bioinformatic methods was used to analyze these profiles.We found consistent differences among the gene-expression patterns associated with acute rejection, nephrotoxic effects of drugs, chronic allograft nephropathy, and normal kidneys. The gene-expression patterns associated with acute rejection suggested at least three possible distinct subtypes of acute rejection that, although indistinguishable by light microscopy, were marked by differences in immune activation and cellular proliferation. Since the gene-expression patterns pointed to substantial variation in the composition of immune infiltrates, we used immunohistochemical staining to define these subtypes further. This analysis revealed a striking association between dense CD20+ B-cell infiltrates and both clinical glucocorticoid resistance (P=0.01) and graft loss (P<0.001).Systematic analysis of gene-expression patterns provides a window on the biology and pathogenesis of renal allograft rejection. Biopsy samples from patients with acute rejection that are indistinguishable on conventional histologic analysis reveal extensive differences in gene expression, which are associated with differences in immunologic and cellular features and clinical course. The presence of dense clusters of B cells in a biopsy sample was strongly associated with severe graft rejection, suggesting a pivotal role of infiltrating B cells in acute rejection.

Abstract

Rodents and dogs conditioned with total-lymphoid irradiation (TLI), with or without antithymocyte globulin (ATG), have been shown to develop mixed chimerism and immune tolerance without graft-versus-host disease (GVHD) after the infusion of major histocompatability complex (MHC)-mismatched donor bone marrow cells given alone or in combination with an organ allograft.Four human leukocyte antigen (HLA)-mismatched recipients of living donor kidney transplants were conditioned with TLI and ATG posttransplantation and infused with cyropreserved donor granulocyte colony-stimulating factor (G-CSF) "mobilized" hematopoietic progenitor (CD34+) cells (3-5x10(6) cells/kg) thereafter. Maintenance prednisone and cyclosporine dosages were tapered, and recipients were monitored for chimerism, GVHD, graft function, T-cell subsets in the blood, and antidonor reactivity in the mixed leukocyte reaction (MLR).Three of the four patients achieved multilineage macrochimerism, with up to 16% of donor-type cells among blood mononuclear cells without evidence of GVHD. Prolonged depletion of CD4+ T cells was observed in all four patients. Rejection episodes were not observed in the three macrochimeric recipients, and immunosuppressive drugs were withdrawn in the first patient by 12 months. Prednisone was withdrawn from a second patient at 9 months, and cyclosporine was tapered thereafter.Multilineage macrochimerism can be achieved without GVHD in HLA-mismatched recipients of combined kidney and hematopoietic progenitor transplants. Conditioning of the host with posttransplant TLI and ATG was nonmyeloablative and was not associated with severe infections. Recipients continue to be studied for the development of immune tolerance.

Abstract

Corticosteroids have been a cornerstone of immunosuppression for four decades despite their adverse side effects. Past attempts at steroid withdrawal in pediatric renal transplantation have had little success. This study tests the hypothesis that a complete steroid-free immunosuppressive protocol avoids steroid dependency for suppression of the immune response with its accompanying risk of acute rejection on steroid withdrawal.An open labeled prospective study of complete steroid avoidance immunosuppressive protocol was undertaken in 10 unsensitized pediatric recipients (ages 5-21 years; mean 14.4 years) of first renal allografts. Steroids were substituted with extended daclizumab use, in combination with tacrolimus and mycophenolate mofetil. Protocol biopsies were performed in the steroid-free group at 0, 1, 3, 6, and 12 months posttransplantation. Clinical outcomes were compared to a steroid-based group of 37 matched historical controls.Graft and patient survival was 100% in both groups. Clinical acute rejection was absent in the steroid-free group at a mean follow-up time of 9 months (range 3-13.7 months). Protocol biopsies in the steroid-free group (includes 10 patients at 3 months, 7 at 6 months, and 4 at 12 months) revealed only two instances of mild (Banff 1A) subclinical rejection (reversed by only a nominal increase in immunosuppression) and no chronic rejection. At 6 months the steroid-free group had no hypertension requiring treatment (P=0.003), no hypercholesterolemia (P=0.007), and essentially no body disfigurement (P=0.0001). Serum creatinines, Schwartz GFR, and mean delta height Z scores trended better in the steroid-free group. In the steroid-free group, one patient had cytomegalovirus disease at 1 month and three had easily treated herpes simplex stomatitis, but with no significant increase in bacterial infections or rehospitalizations over the steroid-based group. The steroid-free group was more anemic early posttransplantation (P=0.004), suggesting an early role of steroids in erythrogenesis; erythropoietin use normalized hematocrits by 6 months.Complete steroid-free immunosuppression is efficacious and safe in this selected group of children with no early clinical acute rejection episodes. This protocol avoids the morbid side effects of steroids without increasing infection, and may play a future critical role in avoiding noncompliance, although optimizing renal function and growth.

Abstract

Infants with end-stage renal disease are at highest risk for early graft loss and mortality of any subgroup undergoing renal transplantation. This study evaluates the influence of donor tissue mass and acute tubular necrosis (ATN) on graft survival and incidence of acute rejection episodes in infant and small child recipients of living donor (LD) and cadaver (CAD) adult-size kidneys (ASKs), pediatric CAD kidneys and combined kidney-liver transplants. Methods. Kidney transplants in infants and small children at a single center and those reported to the UNOS Scientific Renal Transplant Registry were analyzed. At Stanford, multi-variate analysis was conducted on 45 consecutive renal allograft recipients weighing < or = 15 kg, mean weight 11.2 +/- 2.6 kg. The UNOS Registry results in age groups 0-2.5 (n=548) and 2.5-5 years (n=743) were compared with age groups 6-12, 13-18, and the lowest risk adult group of 19-45 years. STANFORD RESULTS. Graft survival was 97.8 +/- 0.0 at 2 years and 84.6 +/- 0.1% at 8 years. The incidence of biopsy proven rejection was 8.8% in the first 3 months and 15.5% over the 8-year follow-up. None of the pediatric CAD kidneys had ATN. Rejection episodes were restricted to the pediatric CAD kidneys alone (3/3), with no kidney rejections in the combined pediatric CAD kidney-liver transplants (0/6; P=0.003). Four ASK transplants had ATN (1 postoperative and 3 late), and all predisposed to subsequent acute rejection episodes (4/4), whereas there were no rejection episodes in ASK transplants without ATN (0/32; P<0.001). At 3 years posttransplantation, mean serum creatinines were worse in ASKs with ATN (1.5 vs. 0.9 mg/dL; P<0.001) and in all grafts with rejection episodes (1.2 vs. 0.9 mg/dL; P<0.05). UNOS RESULTS: Among the 5 age groups studied, significantly better (P<0.001) long-term graft survival rates were observed in allograft recipients in the 2 youngest age groups with ASKs without ATN: 82 +/- 3% and 81 +/- 3% for LD and 70 +/- 7% and 78 +/- 4% for CAD recipients in the 0-2.5 and 2.5- to 5-year age groups, respectively, at 6 years after transplantation. Moreover, the projected graft half-lives after the 1st year in the LD groups without ATN were at least equivalent to those of HLA-identical sibling recipients ages 19-45 years: 26.3 +/- 5 and 29.3 +/- 6 years for the 0- to 2.5- and 2.5- to 5-year age groups, respectively, and 23.3 +/- 1 years for HLA-identical transplants. The graft half-lives for CAD recipients without ATN ages 0-2.5 and 2.5-5 yearswere equivalent or better than those for LD transplants without ATN in recipients aged 19-45 years: 15.4+/- 7 and 23.7 +/- 8 years versus 15.0 +/- 0.3 years. Mean serum creatinines were superior in the 2 younger recipient age groups compared with older age groups.Increased donor tissue mass of the ASK or kidney-liver transplants, in the absence of ATN, seems to confer a protective effect to infant and small child recipients of these allografts. This is manifested by a prolonged rejection-free state in the single center experience and enhanced graft survival and function in the UNOS analysis, comparable to HLA identical sibling transplants for LD infant and small child recipients and to LD adult results for CAD infant and small child recipients. To optimize this protective effect by whatever mechanism, absolute avoidance of ATN is essential in infant recipients of ASK or combined kidney-liver transplants.

Abstract

Infants make up the most high-risk, difficult to care for subgroup undergoing kidney transplantation, with the lowest 1- and 2-year graft survival rates of any other age group. The principal causes of graft loss have been graft thrombosis, primary nonfunction, technical error, and irreversible acute rejection.Infants undergoing kidney transplantation can achieve near 100% graft survival at 2 years following surgery, despite their very high-risk status.Analysis of 45 consecutive kidney transplants performed in patients weighing less than or equal to 15 kg during an 8-year period beginning August 1991. Patients included complex referrals from throughout the United States and all received transplants and were cared for by the same pediatric kidney transplantation team.Mean weight at transplantation was 11. 2 kg. Renal failure was due to congenital or urologic causes in the majority (53%) of cases. Size-discrepant adult-sized kidney grafts were transplanted in 80% of patients; 64% received live-donor grafts; 78% were receiving dialysis prior to transplantation; and 27% had extremely small bladders (<20 cm(3)) requiring modification of the ureteral implantation. Excluding 1 transplant-unrelated death, graft and patient survival at 2 years was 100%. Eight-year patient and graft survival rates (for our combined live and cadaver donor series) were 89.6% and 84.6%, respectively. This compares favorably with much lower graft survival in low-risk adult recipients. Delayed graft function occurred in only 1 patient (2%). Rate of incidence of rejection was 9.3% within 2 years of transplantation and the overall rejection rate was 15.5%. No graft was lost to vascular thrombosis, primary nonfunction, technical error, or acute rejection. The mean creatinine level was 53.04 micromol/L (0.6 mg/dL) and 61.9 micromol/L (0.7 mg/dL) at 1 and 2 years, respectively, and 88.4 micromol/L (1.0 mg/dL) at 3, 4, and 5 years after transplantation.One hundred percent 2-year and excellent 8-year graft survival rates can be achieved in what has historically been the highest-risk and most difficult to care for patient subgroup undergoing kidney transplantation.

Abstract

Major, almost insurmountable, deterrents exist to the use of the small capacity, defunctionalized, nonneurogenic urinary bladder in renal transplantation, namely, the technical difficulty in performing a satisfactory ureteral implantation with conventional methods and the potential secondary problems with high grade ureteral reflux and obstruction. Alternatives are less than ideal and include transplantation into a bowel-augmented urinary bladder with intermittent self-catheterization, ileal conduit urinary diversion, or avoidance of transplantation and relegating the patient to life-long dialysis.Eight consecutive patients (ages 13 months to 29 years) with small, defunctionalized urinary bladders underwent a new method of intravesical implantation of the transplant ureter. The mean capacity of these bladders was 18.5+/-13.1 ml (range 6 to 45 ml), with the bladders defunctionalized for a mean 81.6+/-24.3% of the patients' total lifetime. The technique involved placement of the transplant ureter into a shallow, mucosa-denuded, rectangular trough extending from a superiorly placed ureteral hiatus distally to the trigone. We hypothesized that the mucosal margins on the two lateral aspects of the rectangular trough would grow over the anterior surface of the ureter until they met the advancing mucosal edges from the contralateral side to form a natural neosubmucosal tunnel.Posttransplantation cystoscopic examination demonstrated bladder mucosal regeneration and growth over the ureter, confirming the spontaneous development of a good length neosubmucosal tunnel. All patients demonstrated no evidence of ureteral reflux or ureteral obstruction, whereas an immediate prior cohort of four consecutive patients with bladder capacities < or =30 ml showed that three of four had ureteral reflux (P=0.02) and four of four developed hydronephrosis (P=0.002). All urinary bladders in the present cohort enlarged to expected normal or nearnormal capacities. Serum creatinines were stable throughout the entire follow-up period, with the exception of one patient who had rejection episodes. Two patients had urinary tract infections posttransplantation, but there were no episodes of acute pyelonephritis.This novel technique for ureteral implantation successfully capitalizes on the regenerative potential of the bladder mucosa, resulting in a physiological, anatomically natural, and very effective neosubmucosal tunnel. It appears to guarantee success against both ureteral reflux and obstruction, no matter how small the urinary bladder, and offers no hindrance to enlarging the bladder to near normal capacity posttransplantation. The implantation technique is simple and safe, and its use should eliminate the reluctance to use these bladders. Moreover, this procedure offers a major incentive for the successful rehabilitation of small, defunctionalized, nonneurogenic bladders after kidney transplantation.

Abstract

Nationally, results of renal transplantation in infants are inferior to those in older children and adults. Within the infant group, best results are obtained with adult-sized kidneys (ASKs) rather than size-compatible pediatric kidneys. However, transplantation of ASKs into infants has an increased risk of acute tubular necrosis and graft loss from vascular thrombosis and primary nonfunction. The aim of this study was to define and understand the hemodynamic changes induced by ASK transplantation, so that outcomes of transplantation in infants can be improved.Nine hemodynamically stable and optimally hydrated infants were studied under a controlled sedation with cine phase-contrast magnetic resonance at three time periods: before transplantation, 8-12 days after transplantation, and 4-6 months after transplantation. Cross-sectional images of both the infant aorta and the adult transplant renal artery were obtained and blood flow was quantitated. Renal volumes were also obtained, and expected renal artery blood flow based on early posttransplant volume was calculated. In addition, renal artery blood flow was determined in 10 in situ native adult kidneys prior to donor nephrectomy. Supplemental nasogastric or gastrostomy tube feeding was carried out during the blood flow study period to optimize intravascular volume.Mean infant aortic blood flows were 331+/-148 ml/min before transplantation, 761+/-272 ml/ min at 8-12 days after transplantation (P=0.0006 with pretransplant flow), and 665+/-138 ml/min at 4-6 months after transplantation (P=0.0001 with pretransplant flow). Mean transplanted renal artery flows were 385+/-158 ml/min at 8-12 days and 296+/-113 ml/min at 4-6 months after transplantation. Transplanted renal artery flows were less than prenephrectomy in situ donor renal artery blood flow (618+/-130 ml/min; P=0.02 and P=0.0003) and expected normal renal artery blood flow (666+/-87 ml/min; P=0.003 and P=0.001) at both 8-12 days and 4-6 months after transplantation. A 26% reduction in renal volume (P=0.003) occurred between the two postoperative time periods, and this paralleled the decrease in posttransplant renal artery flow. One-year graft and patient survival in the nine infants was 100%. The mean serum creatinine levels at 3, 6, and 12 months were 0.43+/-0.10, 0.48+/-0.15, and 0.49+/-0.16 mg/dl.This study is the first to quantitatively document the blood flow changes occurring after ASK transplantation in infants. There was a greater than two-fold increase in aortic blood flow after ASK transplantation, and this increase was sustained for at least 4 months and appeared to be driven by the blood flow demand of the ASK. However, actual posttransplant renal artery blood flow was significantly less than normal renal artery flow. Our study suggests that aggressive intravascular volume maintenance may be necessary to achieve and maintain optimum aortic blood flow, so as not to further compromise posttransplant renal artery flow and to avoid low-flow states that could induce acute tubular necrosis, vascular thrombosis, or primary nonfunction.